Digital cameras have become quite prevalent in today's society due to relatively low cost as well as ever-increasing quality of images obtained through use of digital cameras. For instance, many mobile telephones come equipped with digital camera technology, wherein such cameras can be of the order of three or more megapixels in resolution. An image printed with this resolution, for example, on a three inch by five inch piece of photo paper can be of substantially similar quality to an image printed through conventional film techniques.
When obtaining an image through use of a camera (digital or otherwise), an amount of exposure time for a particular image is often determined to improve image quality. Many conventional digital cameras include a separate exposure meter that observes a substantially similar field of view as seen through a lens of the digital camera. In some conventional digital cameras, this exposure meter can be activated by partially depressing a button on the camera. The exposure meter then determines an average intensity value that allows computation of an exposure time for an image that is to be taken through use of the digital camera. Such exposure meters, however, require additional electrical and optical components, thus rendering the digital camera more complex (and expensive). In addition, in such a camera it is not practical to obtain images at a relatively high frame rate such as between five and twenty-five frames per second.
In digital cameras that are configured to obtain images at a relatively high frame rate (e.g., five to twenty-five frames per second) exposure time for an image is typically determined through analysis of a previously captured full resolution image. More particularly, a conventional digital camera can record a series of full resolution images and can set an exposure time for a subsequent image based at least in part upon image content of a previously recorded full resolution image. In environments, however, where amount of light can change quickly, using a previously recorded full resolution image may cause an exposure time to be suboptimal for a subsequent image.